Plotting machine



Dec. 5, 1944 R. M. MacLEOD 2,364,153

PLOT'IING MACHINE Filed Marh 29, 1945 s Sheets-Sheet 1 INVENTOR. 5.50)" 41 Mz/z Z500,

BY I

Dec. 5, 1944. MacLEQD 2,364,153

PLOTTING MACHINE Filed March 29, 1943 3 Sheets-Sheet 2 FIG. 4.

Patented Dec. 5, 1944 UNITED, STATES PATENT: OFFICE PLOTTING MACHINE I Robert M. MacLeod, East Pasadena, Calif.,- as signor to Var-d, Inc., Pasadena, Calif., a cor poration of California I r Application Ma malian, Serial No. 480,896.

ciai (c1. as-40,2

My invention relates to a plotting machine and has particular reference to an apparatus for solving vector triangle problems which finds particular utility when used as a navigating aid on aircraft.

In the navigation of an; aircraft the existence of a wind and particularly a cross-wind willshift the, track or actual course of the plane relative to the ground from the apparent course or head ing which isindicated by the aircrafts compass. The presence of a wind will also cause the actual velocity of the aircraft relative to the ground to be differentfrom the air speed which is indicated by the usual air speed indicators. i Itis thus necessary for the pilot or navigator of the aircraft to take the wind into account in determining the heading or compass direction in which, theplane should be directed in order to cause it to pursue a givencompass course with respect to the ground. The wind must. also be taken into consideration in determining the ac; tual velocityof the plane with respect to the ground which in turn determines the length of timethe plane must fly at a given indicated air speed to traverse a selected distance. l

The taking into account of .the wind requires the solution of a vector triangle consisting of the wind direction and velocity, the air speed of the and direction of the apparent course of the aircraft, the actual course of the aircraftand any wind which may exist. i l

It is also an object of myinvention to provide a plotter of the character set forth in the preceding paragraph which is mounted upon aparallel motion mechanism to permit the device to be readily moved fromplace to place on the chart. It is additionally an object of my invention to provide a plotter which includes means for reproducing mechanically the vector triangle involved in the solution of a particular navigation problem. i i l It is a still further object of my invention to provide a plotter of the character set forth in the preceding paragraph which includes also means for indicating the magnitudes of the linear and angular dimensions of the vector triangle,

It is an additional object of my invention to include in a plotter of the character set forth hereinbefore a drift angle protractor for indicating directly the angle of drift resulting from a cross-Wind; i J p r i Other objects andadvantages of my invention will be apparent from a study of the following specifications, read connection with the accomplane and the heading or compass course being i i followed, and the tracker desired course to be followed bythe plane, and the actual velocity of the plane along that course.

Prior to my invention it was the practice to solve such problemsgeometrically andrecently certain mechanical aids in the nature of slide and introduced into the calculating device. The

panying drawings, wherein:

Fig. 1 is a plan view illustrating the general formfand appearance of the preferred embodi ment of ,my invention, the plotter being illustrated as comprising the head portion of a drafting machineof the endless band and pulley. type;

Fig. 2 is an exploded perspective view illustrating the clamping]. mechanism which is used to lock the wind scale at any desired setting;

Fig. 3 is a cross-sectional view illustrating the details of construction of the pivotal connection results of the calculation: mustthen be appliedto the chart :asby means of scales and protractors calculation. Such an operation presents many opportunities for errors and also requires: the

'"45 before it is possible to ascertain the result of the expenditure of a considerable timeunder ,cir

high speed calculations are directly in connection with, a chart or map to solve vector triangles involving the magnitude between the wind scale and the track scale;

Fig; 4 is an enlarged plan view of thecalculator portion of the plotter, showing the relative position and arrangement of the various scales which are employed to indicate the magnitudes of 'the various quantities involved;

Fig. 5 is a vector diagram illustrating graphically the vector diagram which is reproduced by pivotal interconnection of the heading arm with the track arm; and i Fig, 8 isan exploded cross-sectional View taken mechanism 2 is illustrated in Fig. 1 as being se I cured as at 3 to the upper edge of a table or chart board 4 upon which is placed or held a chart 5. i l

The plotter I is best illustrated in Figs} and 6 and comprises a protractor scale 6 with which is associated a wind arm I, a track arm 8' and a heading arm 9, the arms I, 8 and 9 being adjustably associated to reproduce the vector triangle,

the solution of which is desired. The plotter I is, according to the preferred embodiment of my invention; formed as the pro: tractor head of the parallelmotion mechanism 2 so that it may be moved to any desired position on the chart 5 while preserving a given. angular orientation. To this enduuthe parallel motion mechanism 2 includes a pulley bracket I within whichyis positioned an antifriction bearing such as the ball bearing I I; the outer race being pressed into, a suitable recess provided in the bracket I 0. The inner race; of the ,bearing II receives a spindle sleeve I2 which isthreaded at one end to receive a clamping nut I3 and headedat the other end as indicated at I4. The sleeve I2 i n passed thr h e e ra hu I Q? a P lle hi fo ms. th hs snd. Pi 9v of t e perallsllmoiion mechanism 2'. The pulley hub I5 and the hearing I! arslemre b we f the head I4 and the t I3 by vvhicl 1 mepu uey I6 is journaled for rotation relative to; the bracket I one pulley 16 1s arranged .tofsup'p'or't the protractor 6 and the arms I, 8 ahfdQ. For this purpose the underside of inepuirey I6 is turned to define a downwardly projecting boss I'I which is surrounded by a mounting ring I8' secured to the fpulley as by means bf':sor' ews I9; The protracto'r'plate sissy a1'soeii'circle'th'e boss I1 and be held against axiar pulley I6 by means of a sher -like retaining ring 22 which is clampe'd solidly against the under surface oi the pulley I6 by means of screws 20. The outside diameter ofytl'l'eietaihihg ring 22 is made larger than the inside diameter of the protractor plate 6 and the piate 6 is notched as in- 'dicated at 23 to receive the retaining ring 22.

By this constructionftheprotractor plate 6 is ring-like portion 21 which rests upon the upper surface of the protractor plate 6 and surrounds an upwardly extending boss 28 formed thereon and serving as a guide or journal about which the ring portion 21 is freely rotatable.

The outside diameter 'of the boss 28 is preferably made somewhat less than the outside diameter of the mounting ring I8 so that the ring portion 21 is received in as annular groove and below the; ring portion 21 is formed with a T-slot ir i which isreeeiyedj the rectangular head 29 of a El'ainpscrew 30. IA locking nut 3| threaded .upon

veirie'nt "relative to the held against axial movementbut is mounted upon the pulley I6 for "angular adjustment relative thereto. This permits the origin "or 'zero of the protractor plate to 'be"tu'rned to desired posi' tion so that it may b'e alignedi'ndirection 'withthe North-"South ordinate of 'thechart 5. k

In'order that the protractor ring'niay be locked inits adjusted position, a locki'ng screw 24 having arectangularhead 25 is positioned in a T-sl'ot formed in the upper surface of the protractor ring 6. The screw 24 isjexten H clearance hole in themoun ingring =I8 to receive on its upper "end a clamping nut 26 which, upon being turned, will clamp the protractor ring socurely against the under surface of the mounting na I8. a i

The protractor plate '6 likewise'serves as-a support for the heading arm '9. The arm -9' hals a general shape and form which is best illustrated in Fig. 4 and which is characterized'by a large upwardlythrough a I the upper end-of the screw 30 serves to clamp the ring portion 21 to the protractor plate 6 and lock these two elements against rotation relative to each other. v The wind scale I preferably comprises a short flat member of trapezoidal cross section which is received in a similarly snapeagroove formed in a clamping element 32. The eleiher'it 32 comprises a substantially solid cylindrical member which is received in a westerners formed in the under side of the pulley |6. rom the ineinber 32 rises avertical shaft which passes upwardly through the interior or the spindl'e sleeve I2. Each or the parts I, I2 and 32 are shown in perspective in Fig.2. v I

The upper end -or-- tne stem at is threaded to receive a clamping 'p la-tet'liwhich is secured to the under surface of a lgnob pr hand wheel 36 as by means 'of'screws "31. The clamping plate 35 normally rest's'up'on the upper surface of the nut 1-3 so that when the plate is rotated as by turning the kno '36, w stern at will'b'e moved upwardly to lift tneuampm element 32, a clearance space 38 being provided for this purpose vented Hy "the engagement of its upper surface with the under surface er the pulley boss. The sloping surfaces or the ehannei in the mem be! '32 'ale thus bioiiht into firm frictional engagement with slopihgsides of the wind scale "I and so look the wind scaie against sliding-moverrient relative ilo the cramping elements.

. Furthermore, the knot at released to permit tree sliding :mdvemnter the wind scale 1 the sa me is *reeiy rater-able about the axis or the "scan at, this'rotation' being permitted by rotation or m eiemerlt-az. when, however; thekno'b as is turnedto-lock the ixfi nd' 'scale 1 against sliding movement, 'the scale 1- is 'cl'ainped securely 'against'the under s r'fa'ce of "the-pulley 1'6, thus effecting. a looling 'o the scale 4 against angular movem'entaswella slidirig mo've em; a

The wind scale 51 (eXte'ndsacross and lies the upper' surface of' the track 8 and-is pivotally'connected to the ar m 8 iii the manher which is 'illusti"ated in Fig. s. The time share I is bored and counterbored from its upper -sii'rrace to rec'e'i've a pivst sc'rw- 3a which is threaded into ='a suitable thraded fns'ert' tu -pressed or otherwise suitably sets-r d in "the track arm s.

' arms.

trated in Figs. 7 and s as'comprising a shoulder 44 in place, the thickness assigns By-this means the trackarm 8 is pivotally 0611 nected to the wind scale 'l for free pivotal movej The track arm Band the headingarm 9. are both longitudinally slotted as indicated; respecable pivot structure indicated generally at 43 which serves the dual purpose; of providing a pivotalinterconnection of thearms 8 and 9 and ameans for changing the effective lengthof these The pivot mechanism 43 is best illus The inner portion of the heading arm 9 where it joins the ring-likeportion zlisprovided with a windowor aperture 51 through which a pro]- tractor scale 58 inscribed ontheupper surface of the protractor plate 6 maybe observed. The

shape of the heading arm 9 is best shown in Fig.

6 as being bent downwardly over the sloping up per surface of the protractor plate 6 and as having a central portion-59 depressed to bring the upper surface thereof, upon which is inscribed a witness point 60, intothe plane of the upper surcate the magnitude of the true ground speed of the aircraft upon a scaleor set of graduations 41fsuitably inscribed upon theuppersurface of thetrackarnifi. i i

The drift protractor 45 is bored as indicated at 48 'to receive the shoulder portion of the pivot screw 44. Upon the undersurface ofthedrift protractor 45 there is formed a longitudinally extending key or rib 49 having. a width adjusted to be closely received within the slot 4| by which means the protractor is held in a fixed angular 1 position relative to the track arm 8'. Upon the upper end of the pivot screw 44 there is threaded a drift pointer 50. The pointer 50 screwsdown against the shoulder of the shoulder scrw'44 and serves to hold the shoulder screw its key 49 being adjusted to provide some clear; ance between the protractor pointer 50 andthe upper surface of the track arm 8 so that the assembly of protractor pointer 50 and pivotscrew 44 may be rotated relativeto and the drift protractor 45.

The protractor pointerv 50 is provided on its upper surface with a longitudinally extending rib or key 5| having a width adjusted to be closely received within the slot 42 in the heading arm 9 so that the pointer 50 is held position relative to the heading arm9 so that the angular relation between the arms 8 and 9 maybe indicated by the angular relation of the pointer 50 relative to a protractor scale 52 suitably inscribed on the upper surface of the protract or45.

Upon the upper end of the screw 44 and above theheading arm 9 there isplacedja pointed mem;

arm 9 and indicateon a suitable set of gradua tions 54 inscribed onthe upper surface of the arm 9 the true air speed of the air craft. To hold the pointer member 53 at right angles to the length of the heading arm 9, the same isproarm 6.*againstmovement relative to each other.

Such a locking of the assembly leaves-the entire -assembly free to slide along the length of the slct 4| in the track arm 8.

ofthe member 45 and in a fixed angular face of the protractor plate 6,thus permitting the angularposition of the heading arm 9 to be readily observed. The wind scale 1 isprovided on its upper surface with a set of graduations 6| representative of various wind velocities. The

graduations which are shown in Fig. 4 are in tended to be read at the point where the scalepasses under the outer periphery of the protractor plate 6. 1

I'have shown in Fig. 5 the vector triangle which is solved by the device above described.* In Fig.

5 thelines 1', 8' and 9' represent the efiective lengths of the wind scale 1, the track arm 8 and the heading armf9, the lengths and angular rela tions of these arms being determined by the posi tions of the three pivotpoints 342-99" and 44' corresponding respectively to the axis 34 of the pulley IS, the pivotal connection 39 between the iso windscale 1 and the track arm Brand the pivot screw 44 which serves to interconnect the track arm 8 andthe leading arm 9. i

In the vector diagram of Fig. 5 the arm lt represents the magnitude and direction of the wind relative to the surface of the ground and the line 8 represents the direction of the air: crafts velocity relativetothe ground, while the length of the line S'represents the magnitude of the aircrafts Velocity in air. Thus the length of the line 8' is fixed and represents thevelocity of the aircraft relative to the surface of the heading to be followed by the aircraft. Likewise ground and the angular positionof the line 9" is "similarly fixed to represent the direction or the angle representedby the dimension line bearing the reference character 62 comprises the drift 1 angle or angular relation between the apparent ber 53 which is adapted to overlie the heading course or heading of the aircraft and the actual course or track of the aircraft relative to the surface of the ground. This angle is indicatedi asshown at 62" on the drift protractor 45;

In placing the mechanism in operation,the protractor scale is. first adjusted with respect.

tothe parallel motion mechanism to place the North-South or meridian lines of the chart 5.

- windscale 1 inthe zero position, by which operation the pivot points 39 and 44 are placed in coaxial positions. The heading arm 9 is then turned until the witness point is opposite the zero 63 on the protraotor 6 and theheading arm 9 is then looked to the. protractor by the clamping nut 3| The clamping nut 26 for the proposition alignedwith the meridian lines of the chart 5. The clamping nut 26 is then employed to lock the protractor plate 6 to the pulley I 6 protractor plate 6 will thereafter be held in the proper fixed orientation relative toithe chart 5.

The problem which frequently confronts a navigator is that of determining the headingor com.

index or zero (63 in Fig. 4) in alignment with the tractor scaleis released whereupon the arms 8 and 9 (now parallel to each other) are turned toa of the parallel motion mechanism so that the course. between two selected locations indicated on the chart 5. A concurrent problem is that of determining how long the aircraft should be flown along that heading to reach the desired destination. In the solving of such a problem the wind scale I, the track arm a and-heading arm 9 are each released through manipulation of the knob- 36, the clamping nut 56 and the clamping nut 3|.

- The pivot. assembly 43 may then be slid along the slot 4.2 in the heading arm 9 until the pointer 53 indicates on the scale 54. the true air speed at which the aircraft will be operated.

When so adjusted the assembly 43 may be locked to the heading arm 9 by turning the clamping nut 56... The Wind scale'is then turned to a position such that a longitudinal line 64 inpositioned to engage the member 32 in the treme positionsof the scale 1.

.By sliding the. Wind. scale 1 to a position such. that the. edge of the protractor plate 5 indicates on the graduations. 61 the known. magnitude of the wind, the. wind-scale. may be set to conform to that known magnitude. When the scale I is thus. set. to conform. to the known magnitude and direction. of. the wind, the same is locked. by turning. the knob 36...

When these preliminary operations are com.- pleted, the plotter is, moved overthe. surface of the chartb and. the. angularposition of the arms 8 and 9,- adjusted until, one edge of the: arm. 8 may be. so laid. on. the. chart. as. to. join. the starting point of the aircraft withthe proposedv destination. Such a. movement of. the arms. is permitted. by the. free; pivotal connection of the. arm 81 to the wind. scale. 1,. the. sliding connection between. the arms. 8 and 9.. and the free pivotal connection ofthe arm 9. to. the protractor 6.

.When the arm. 8 is. positioned. as. described, it

then. defines. on the chart. 5 the proposed track or course. of the aircraft relative. to. the. surface. of

the ground.- The. entire assembly may then be.

locked against relative movement of the parts by lockin the. heading, arm 9. to. the. protractor 6 through manipulationof the clamping. unit .31... It. will beseen that this operationserves. to fix. the length of two. sides of the triangle and the magnitude. of the included angle so that the shape of the. triangle is finally determined;

Having. thus set the. instrument, the heading. or compass course to, be followed by the aircraft in. order to pursue the desired course relative. to the groundsurface may then. be. read onthe pro.-.

I tractor scale 6 opposite the. witness point. but.

To. calculate the. time. of the. proposed. flight. the. actual speed of the aircraft. relative to the ground. may be. read on the graduations 41 of the. arm. 8 opposite the pointer 46.. Likewise. the angleof' drift may be. determined by reference;- to the'driftprotractor 415..

The drift. protract'or. 45 may be. used. those cases where the probable. direction of the wind is well. known, as. when. flyingin a location. where. certain. prevailing. winds. exist. hut'where. the. actual magnitude of. the wind. is. not. known. In such. circumstances. thedlift angle may be determined throughthe use of; a conventional drift.

indicator. Thereafter with the'pivot assembly 43 locked to the heading arm '9 at the two air speed of the aircraft, the arm .9 is released from the protractor scale 8 and the wind scale 1 is released through manipulation of the knob 38 and manually heldin a position corresponding;

to the known direction'of the prevailing winds,

while the arm 8 is so placed as to extend between the starting point and the desired destination on the chart. Bythen sliding the protractor plate along the wind scale to a position such that the previously determined angle of drift is indicated on the drift protractor 45, the vector triangle is established. The knob 36 and the clamping nut 3| may then each be manipulated to lock the wind scale I and the heading arm 9. The desired headingmay then be read on theprotractor scale 6 opposite the witness point 60. t

A problem which is the converseof that described exists when the heading, drift angle and wind direction are known and it is desired to determine the actual course of the plane relative to the surface of the ground. In such a case the heading arm 9 is locked to the protractor plated at the known heading and the pivot assembly 43 is locked to the heading arm 9 at the known true airspeed of the aircraft. With the knob 36 released, the wind scale may then be slid relative tothe protractor plate 6 while being manually held. in an angular position corresponding to the known windv direction until the known angle. ofv drift is indicated on the drift protractor 45. When. this condition obtains the triangle may be fixed. by locking the'k-nOb 36. The track arm 8 By virtue of the adjustable features of the device of my invention the. plotter may be sooriented with respect to the. board that it is unnecessary" chart itself.

From the foregoing it will be observed that; I

is then held in an angular position'relativefto the chart .5 corresponding to the direction of flight of the aircraft.

It. will be notedthat six variable quantities are involved in the determinations made by the plotter; namely, three directions and. three magnitudes. Furthermore, the fixing of any four of these six quantities determines the remaining two so that with the plotter of my invention, if any.

four of the quantities are known, the other two. may be determined. Furthermore, these calculations are made with reference to the chart 5,

thus eliminating the necessity of any transfer of. information from. a calculatingdevice to the have provided a vector plotter which is particularly adapted to the solution of the vector triangle problems raised. in the navigation of aircraft's The device of my invention is so arranged. as to permit it 'to be used directly on. a chart-secured to the chart board. which. carries the instrument.

to take into account the angular orientation of the coordinate system of the chart in determin-.

ing, the various directions involved. Instead each direction is referred to the North-South line the aircraft...' Y V g It will. be. seen. that. the device. is smalluand compact so. that it. may be inexpensively manu factured and constructed to have a very light weight. particularly adapting. it. to use onaircraft.v

. While l'have shown. and describedthepreferredembodiment of my invention. I do not-desire toof the-compass being used. to. guide the flight. of: I

Iclaim: i

In a plotting instrument, a support having formed therein a recess extending upwardly from the bottom thereof, a scale having two parallelly disposed side surfaces and two angularly disposed side edges,a clamp member disposed below said support and having a channel formed in one surface thereof with a cross section congruent with clamping member being mounted for vertical movement in said recess, means on said clamping member engaging said support to support said scale for pivotal movement, and means attached to said clamping member for drawing the same upwardly to wedge said scale between said clamp ing member and said support to thereby secure said scale against sliding and pivotal movement.

ROBERT M. MACLE D. 

